1. Field of the Invention
The present invention relates to building construction and the like, and particularly to interlocking and insulated construction blocks for forming walls with a relatively high U-value.
2. Description of the Related Art
The “U-value” of a building element is the inverse of the total thermal resistance of that element. In other words, the U-value is a measure of how much heat is lost through a given thickness of a particular material. The efficiency desirability of insulated construction materials is generally measured by the U-value of the material. A common and relatively simple method for increasing the U-value of a wall is to affix a layer of insulation material thereto. In such common constructions, the insulated layer is then covered with a special type of render (i.e., plasterwork) or cladding, thus forming a two layer system; i.e., one insulating layer and a second outer layer for weather protection.
Another conventional construction method for further increasing the U-value involves using two leaves of hollow block wall, with the inner leaf of the block wall being relatively thicker. In such constructions, the two leaves of the wall are separated by a thermal insulation layer. The outer surface of the wall is protected against weather by plastering or affixing tiles. Thus one layer is for insulation, and a second outer layer is for weather protection. Typical insulation materials include expanded and/or extruded polystyrene, mineral wool, polyurethane foam and phenolic foam.
The thickness of the thermal insulation layer is determined based on the heat transmission characteristics of the different materials used in the construction of the wall and the U-value requirements of the region. The U-value requirements ultimately depend on the weather conditions of the region, which are typically measured in terms of the degree-days. The use of conventional two layer systems of the thermal protection is not only expensive, but also time consuming. Further, the attachment of the layers requires special care due to a high risk of frequent failure and detachment. Additionally, although conventional construction blocks of one wall thickness (typically on the order of 20 cm wide) are available with one layer of insulation, the insulation is usually not enough to meet the U-value requirements of extremely hot arid regions. Thus, interlocking and insulated construction blocks solving the aforementioned problems is desired.